Docosahexaenoic acid (DHA, 22:6n-3) is a long-chain polyunsaturated fatty acid member of the n-3 fatty acid family. DHA is important in early development, both in terms of the reproductive physiology of gestation and in postnatal behavioral and cognitive function. In adults, DHA has been shown to lower triglycerides and is important to cardiovascular health and autonomic control, lowering heart rate (HR) and blood pressure and increasing heart rate variability (HRV). However, very little is known about how n-3 fatty acids impact cardiac autonomic control in infants, children or the fetus. In the course of using a non-invasive fetal biomagnetometer to record and characterize aspects of fetal autonomic control of heart rate and variability and other neurobehaviors, we identified a group of women who were taking commercial DHA supplements during their pregnancy. In this small sample, we found lower fetal heart rate and higher fetal heart rate variability. This suggests that maternal DHA intake during pregnancy may have an effect on fetal cardiac autonomic control that results in lower mean heart rate and higher heart rate variability. To date, no one has investigated the effects of maternal DHA supplementation during pregnancy on fetal cardiac measures of rate and variability. The specific aims of this project are to evaluate the effect of maternal DHA supplementation during the 2nd and 3rd trimesters of pregnancy on maternal and fetal cardiac measures of rate and variability and fetal movements at 24 and 36 weeks gestational age. Additionally, we plan a postnatal assessment to determine the effect of supplementation on newborn neurobehavioral organization and infant heart rate and vagal control. This proposal is designed to test the hypothesis that maternal DHA intake (600 mg per day) given during the last two trimesters of pregnancy will increase maternal red blood cell phospholipid DHA and thus will have a positive influence on fetal cardiac autonomic nervous system regulation reflected in higher vagal control (reduced HR) and increased HRV. DHA will be provided via algal oil capsules while the placebo group will be provided capsules containing a combination of soybean and corn oils. This proposal is novel in that: 1) it is the first longitudinal exploration to determine the effects of maternal DHA supplementation during pregnancy on cardiac autonomic nervous system control of rate and variability from the 24 weeks gestational age to 2 months postnatal age 2) it is the first to explore the effects of supplementation during pregnancy on newborn neurobehavioral organization and 3) it uses a novel technology that is well suited to simultaneously measure the maternal and fetal magnetocardiogram (MCG) and fetal movements PUBLIC HEALTH RELEVANCE: Optimal fetal neurodevelopment is dependent on nutrients exclusively derived from dietary sources, including docosahexaenoic acid (DHA). DHA supplementation is of general public health interest because studies in adults have shown that dietary intake of DHA affects several cardiovascular disease risk markers including blood pressure and heart rate. The results of this study may have significant implications in regard to maternal- fetal nutrition, fetal programming of autonomic nervous system control, cardiac regulation and future cardiac health.